Kiri:Moto is the plugin for Onshape. It is also a stand alone browser based app that you can use with an SVG or an STL of your own. You can also download it and install it locally. I have played with it in CAM mode. Mostly I use it to make SVGs of the models I make in OnShape. It is absolutely the best resource for making OnShape laser friendly. I haven’t quite gotten to making it useful for CNC work though. Not quite sure about it. I use EstlCAM and I am very pleased with what it does. Takes some time to get familiar with it.
Here is a good explanation of it.